ART. 17. NORTH AMERICAN PHOROCERA ALDRICH AND WEBBER. 31 



gated. Thorax black, gray pollinose, marked with four black vittae ; 

 three dorsocentral macrochaetae ; scutelhim black with three pairs 

 of marginal bristles besides the shorter upright pair of apical om^s; 

 sternopleura with four bristles. Abdomen black, gray pollinose 

 without pattern; first segment with one pair median marginals, sec- 

 ond with one pair each of median discal and marginal, third with one 

 ciliate at most. Wings hyaline, the small crossvein clouded with 

 rows on the apical half which are three-fourths as long as the 

 macrochaetae of the third segment. Legs black, mid tibiae with two 

 bristles on the outer front side near the middle; hind tibiae sub- 

 ciliate at most. Wings hyaline, the small crossvein clouded with 

 brown, apical cell almost closed, ending nearer the wing tip than in 

 most of the other species of this group: third vein with two or 

 three bristles at its base. 



Length 7 mm. 



Described from one male specimen collected at Koehler, New 

 Mexico, by W. R. Walton, August 14, 1913. 



Type. — Male, Cat. No, 25696, United States National Museum. 



Subgenus Parexorista. 



ZENILLIA CHELONIAE Rondani. 



Exorista cheloniae Rondani, Prod. Dipt. Ital.. vol. 3, 1859, p. 120. — 

 CoQurLLETT, Revis. Tachin., 1897, p. 92. — Tothill, Can. Ent., vol. 45, 

 1913, p. 70.— Gibson, Ann. Rept. Ent. Soc. Ont, 1911, p. 117. 



Parexorista cheloniae Townsend, Proc. Ent. Soc. Wash., vol. 13, 1911, 

 p. 165; and vol. 18, 1916, p. 19.— Howard and Fiske, Bull. 91, Bur. 

 Ent, 1911, p. 297. 



Abdomen brownish or black, sprinkled lightly with gray pollen 

 and without sheen; legs usually brownish; face gray pruinose. 



Front of male 0.25 to 0.28 (in three), in the female 0.30 to 0.38 

 (in three) of the head width; face and front gray pruinose, blackish 

 at vertex; the sides of same with many fine hairs; parafacial some- 

 what narrower than the parafrontal and at the narrowest part 

 barely the Avidth of the third antennal joint: bucca linear, one- 

 twelfth the eye height; facial ridges bristly on the lowest fourth; 

 palpi yellow; third joint of antennae in both sexes two and one- 

 half to three times the length of the second; arista thickened on the 

 basal fifth, the penultimate joint short. Thorax black, gray polli- 

 nose marked with four or five black vittae and bearing four dorso- 

 central macrochaetae; scutellum yellowish w^th four pairs of mar- 

 ginal bristles all of about the same size ; sternopleura thickly clothed 

 with fine hairs, and bearing two bristles. Abdomen brown or 

 blackish (sometimes the sides of intermediate segments yellow) 

 gray pollinose and without sheen. Discal macrochaetae present of 

 various sizes but not ariitnged in pairs, blending with the erect 



559«}_24— I'r()C.N.iM.vol.()3 30 



